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AssigneeDenso Corporation
InventorsYasuhiro Shimizu, Kiyoshi Tsurumi
Estimating the term…
In a vehicle navigation apparatus having a control section which calculates relative vehicle positions and travel direction by dead reckoning calculations based on outputs from on-board sensors and periodically acquires GPS measurement data via a GPS receiver and applies error-reduction filter processing to these data to obtain position and travel direction information for correcting the calculated relative positions, the apparatus has a function for detecting that a travel direction obtained by dead reckoning contains an excessive error, and when that condition is detected, for directly applying an estimated vehicle position and travel direction derived directly from the GPS data, without filter processing, to correct the corresponding relative position and travel direction estimates. Rapid correction can thereby be achieved when the vehicle has been operated in a condition whereby a large amount of error has suddenly arisen in the travel direction that is estimated by the apparatus through dead reckoning calculation, e.g., after the vehicle has been rotated on a turntable with the vehicle navigation apparatus inoperative.
A vehicle navigation apparatus including sensor means (60, 62) for producing signals indicative of amounts of change in heading direction of a vehicle and amounts of change in distance traveled by said vehicle, current position calculation means for calculating successive current positions and travel directions of said vehicle based on said signals produced from said sensor means, and including GPS (Global Positioning Satellite) receiving means (64) for receiving radio waves transmitted from a GPS system and for thereby deriving position measurement data relating to said vehicle, means for applying predetermined filter processing to said position measurement data, and GPS correction means for periodically applying data resulting from said filtering processing to correct respective errors in said current positions and travel directions which are calculated by said current position calculation means, to obtain corrected current positions and travel directions;
4 A vehicle navigation apparatus as claimed in claim 3, wherein said vehicle navigation apparatus comprises means functioning subsequent to said registering of said reference position for calculating respective vectors extending from said reference position to said first position and to said second position, and wherein said deviation is judged as an angular difference between said vectors.
A vehicle navigation apparatus as claimed in claim 4, wherein when it is judged by said error judgement means that said angular difference exceeds a predetermined amount, said GPS correction means performs correction of an estimated travel direction which is calculated by said current position calculation means, by rotating said estimated travel direction through an angular amount which is identical to said angular difference.
Dependencies are inferred from the claim text.